OBJECTIVETo explore effect of polymorphism rs1563828 (C > T) in human murine double minute 4 gene (MDM4) on genetic susceptibility for early-onset breast cancer and potential association with age of onset of breast cancer.

METHODSOne hundred and twenty-four early-onset breast cancer patients (age ≤ 35 years at time of diagnosis) from independent families admitted from January 2006 to June 2010 and 101 age-matched healthy control subjects were analyzed. Genotype analysis was conducted by polymerase chain reaction and then MALDI-TOF-MS assay. Association of genotype distribution and breast cancer risk was evaluated by χ(2) test. The odd-ratios (OR) and 95% confidence intervals (CI) were calculated by unconditional Logistic regression model. The t test was used to compare the age and demographic differences among groups.

RESULTSThe frequency of rs1563828 polymorphism genotypes in control group were CC 43.6% (44/101), CT 42.6% (43/101), TT 13.9% (14/101), and in case group were 42.7% (53/124), 46.0% (57/124), 11.3% (14/124), respectively. No significant difference (χ(2) = 0.449, P = 0.799) was reached by χ(2) test. rs1563828CT or TT genotype does not confer a significantly increased risk for breast cancer compared with CC genotype after adjusting for age, menarche in Logistic regression analysis (OR = 1.024, 95%CI: 0.581 - 1.806, P = 0.934). TT carriers were observed to develop breast cancer earlier than CC/CT carriers [(30 ± 4) years vs. (32 ± 3) years, P = 0.028].

CONCLUSIONSThe rs1563828(C > T) polymorphism in MDM4 gene may not confer risk to breast cancer, especially for early-onset breast cancer patients. Homozygous TT of rs1563828 is associated with younger age to develop breast cancer.